Multi-Scale Motion of Soft Continuum Robots using Tendons, Eccentric Rods, and a Cam

Abstract

Continuum and soft robots may offer many advantages for use in miniature diagnostic and interventional surgical devices. Tendon-driven continuum manipulators are simple, robust, and can offer large ranges of curvature through actuation. However, obtaining precision motion at the distal end of a tendon-driven soft continuum manipulator while the robot traverses a tortuous or highly curved path remains a challenging task. We present the design concept and initial proof-of-concept prototype evaluation for a flexible, soft-skinned continuum robot that can exhibit both large-scale bending with tendons and precise motion through the rotation of cam-fitted Nitinol rods eccentric with respect to the axial centerline of the robot. We demonstrate experimentally that antagonistic pre-tension in the tendons allows the small-scale motion to be tailored to a specific axis if desired. Experimental results are demonstrated on a prototype which is 102 mm long and can generate 80° of total bending with the tendons and 6 mm of controlled end-effector motion using the cam rotation.